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Automation and tube testing with positive results

apfelblosm

By apfelblosm
in Transfusion Services

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apfelblosm Explorer

apfelblosm

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So I just took over at a 350 bed hospital.  We have a Neo and an Echo.  We run routines on both and will do panels on both if screen is positive.  

 

Their current procedure is that if they can't rule out everything in the panels on the automation, then they can just run the few cells they need to rule out in PEG-IgG and be done.  Then, they only XM in tube with PEG.

 

This has concerned me since I got here.  My inclination is to either makes them rule out everything in PEG in order to XM in PEG, or to get crossmatching on the NEO and ECHO.

 

Thoughts?

 

Jen, MT(ASCP)SBB

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David Saikin Grand Master

David Saikin

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Personally I'd do the xm's with the automation just because it is probably more sensitive.  If you have to use PeG because the automation panels don't offer the cells I'd still use the automation for the xm's.  If you have to use PeG due to automated rx's that are weak or make no sense and PeG gives you a satisfactory answer then I'd use PeG for the xm's.  I don't think you can find one answer for your dilemna.

 

Not being a solid phase user I wonder - can't you adsorb cells onto a plate and test?  The automation must do that for your xm's.

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L106 Mentor

L106

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Answer to your question, David, is YES.

 

I basically agree with what David has said.  However, we do not routinely do crossmatches on our Echo because:

 

1.  It takes too long

2.  Since the Echo does only the AHG phase of testing, you must do some other method to assure ABO compatibility (such as a tube immediate spin crossmatch, or perhaps a computer crossmatch if your truth table is set up properly, etc.)

 

Donna

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kate murphy Community Regular

kate murphy

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We have a Galileo, a Tango, had an Echo, and do PeG manual. 

The thing with solid phase is that it is extremely sensitive - to real antibodies and "not real" antibodies.

There are many times that a weak Galileo/Tango screen/panel (2+ or less) will not replicate in PeG.  No specificity, a few random cells.

We do a PeG screen and if that's neg, we're done.

If it's a patient with previous antibodies, we might look very closely and avoid an antigen based on the assumption that a responder will usually make more.

You might check and see what validation they've done when the instruments came in.

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David Saikin Grand Master

David Saikin

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I don't see how you can justify using a less sensitive method to validate/invalidate your more sensitive, primary method.  I use gel.  I have found that any reactions of 2+ or less in gel are invariably negative using PeG c tubes - even if enzyme pretreated.  The only time I go to complete tube testing is if I run into a warm auto - I cannot absorb all the auto ab out if using gel - even multiple absorptions. 

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Malcolm Needs Grand Master

Malcolm Needs ☆

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Well David, we quite often go to tube IAT at my Reference Laboratory, precisely because it IS less sensitive than gel.  Tube IAT has served us well for years and years (before that it was tile IAT - wouldn't recommend that - except for resolving antibody mixtures), and I haven't seen the rate of transfusion deaths coming down - at least, not for that reason.

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David Saikin Grand Master

David Saikin

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I have a conundrum - should I ignore rxs in gel that are 2+ or less because they will be negative in tubes?  There is the whole deal with the Ortho screening cell 2.  Ortho came out with what I think are ridiculous solutions - if I tested these in tubes they would be negative.  I have found that sometimes I can get only the R2R2 Ortho panel cells to react.  If I enzyme pretreat, about 80% of the time the reactivity disappears but sometimes I can get other vendor's R2R2 cells to react also (with enzyme).  Invariably the pt is E negative and only the R2R2 cells are reactive . . . but if I used tubes there would be no reactivity. 

 

Maybe I'm being too sensitive!!!  B)

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tbostock Veteran

tbostock

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I have a conundrum - should I ignore rxs in gel that are 2+ or less because they will be negative in tubes?  There is the whole deal with the Ortho screening cell 2.  Ortho came out with what I think are ridiculous solutions - if I tested these in tubes they would be negative.  I have found that sometimes I can get only the R2R2 Ortho panel cells to react.  If I enzyme pretreat, about 80% of the time the reactivity disappears but sometimes I can get other vendor's R2R2 cells to react also (with enzyme).  Invariably the pt is E negative and only the R2R2 cells are reactive . . . but if I used tubes there would be no reactivity. 

 

Maybe I'm being too sensitive!!!  B)

Yes, we've had the same. "Enzyme only" or "gel only" Anti-E antibodies, not detectable in tube or solid phase. Theoretically not clinically significant, but I'm not brave enough to give them anything but E negative.

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galvania Mentor

galvania

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Enzyme only anti-E are very common and mostly non red cell immune.  In my experience they are often really strong in enzymes but negative in Coombs, whereas a  real weak anti-E might  give a weak reaction in enzymes and not in Coombs.  But a lot depends on the enzyme technique used - and I don't mean gel/solid phase/tube; rather I mean 1-step or two-step.....

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David Saikin Grand Master

David Saikin

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Enzyme only anti-E are very common and mostly non red cell immune.  In my experience they are often really strong in enzymes but negative in Coombs, whereas a  real weak anti-E might  give a weak reaction in enzymes and not in Coombs.  But a lot depends on the enzyme technique used - and I don't mean gel/solid phase/tube; rather I mean 1-step or two-step.....

I find the Ortho cells (screening/panel) seem to be extra sensitive and that is why their R2R2 cells react neat (gel).  Other vendor's R2R2 cells are non-reactive unless enzyme pretreated (I do 2 step Papain).  But, as I stated above, about 80% of the time the reactivity is no longer detectable after pretreatment.  I report these out as probably an enzyme sensitive HTLA antibody.  I think I see this phenomenon mostly in multips.  I do not see this phenomenon often.

Edited by David Saikin
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